If you regularly experience heartburn or acid reflux, then you should think about cutting back on carbonated soft drinks. The Week Magazine reports:
"A survey of 15,000 Americans over the age of 40 found that those who drink large quantities of soda often experience heartburn while they're sleeping. Carbonated soda is acidic, can irritate the stomach, and promotes the opening of the muscle that usually keeps stomach acid from flowing upward into the esophagus."
I don't experience heartburn very often, but those times I have experienced it, I've connected it with eating too much. So there's another suggestion: if you experience heartburn, eating less at meal times may also help.